Double taxation agreements (DTA) are treaties concluded to prevent double taxation of income from international activities. Such a treaty between two countries - the country of residence of a taxable person and the source country where the income is generated - regulates the extent to which a country may impose income tax on income earned. The methods used to prevent double taxation are as follows: (1) the exemption method, in which foreign income is exempt from taxation in Germany and (2) the credit method, in which income is taxed in both countries and the country of residence then deducts the tax levied abroad from the (overall) tax burden.

The website of the German Federal Ministry of Finance (only available in German) includes a list of all DTAs into which Germany has entered with other countries.

Source: Wikipedia, edited